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Nuclear Fuel Batch Optimization for Extra Long Equilibrium Core Design of APR-1400
Umarov Shokhmirzo Bakhrom ogli,안정선,하창주 한국에너지학회 2023 에너지공학 Vol.32 No.2
This paper proposes a core design methodology with a systematic approach to nuclear fuel batch optimization. The proposed methodology consists of three major steps: evaluation of core average enrichment and the number of burnable absorber (BA) rods in a core, determination of batch size and batch enrichments, and loading pattern (LP) search. The proposed methodology is applied to design one initial core model and five equilibrium core models. All models satisfy design constraints. For equilibrium core models, the number of feed fuel assemblies (FAs) vary from 92 to 128 FAs, firstly to determine the enrichment requirements necessary to meet 24-month cycle length, and secondly to investigate a relationship between fuel cycle cost and batch size. The results demonstrate that 24-month equilibrium fuel cycle is possible for a number of feed FAs greater than 116 because of the limitations [1] on maximum fuel enrichment up to 5 w/o and maximum burnup of 60 MWD/kgU. Furthermore, levelized fuel cycle cost (LFCC) calculations for 24-month equilibrium core models of APR-1400 show that more than 116 feed FAs of APR-1400 is less economic than 18-month cycle length of OPR-1000 or 19-month cycle length of APR-1400.
Rakhmatjon Umarov,Young-Sik Pyun,Auezhan Amanov 한국트라이볼로지학회 2018 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.6
In this study, we spray a Ni-Cr composite powder onto AISI 4340 steel using the high velocity oxygen fuel method. We subsequently subject the Ni-Cr coating (as-sprayed) to ultrasonic nanocrystal surface modification (UNSM) process to improve the tribological performance. This study aims at increasing the wear resistance and durability of the Ni-Cr coating by altering the surface integrity and microstructure via the UNSM process. The UNSM process reduces the surface roughness of the as-sprayed coating by about 64%, which is explained by observing the elimination of high peaks and valleys and filling up micro-pores. Furthermore, a change in the microstructure of the coating due to continuous high-frequency strikes to the surface by a tip can lead to an increase in hardness from about 48 to 60 HRC. Furthermore, we investigate the characterization of the friction and wear behavior of Ni-Cr coating by a ball-on-disc tribometer in the dry conditions. We determine that after the UNSM process, there is a significant reduction in the friction coefficient of the as-sprayed coating from approximately 1.1 to 0.75. This is owing to the increased hardness and smoothed surface roughness. In addition, we investigate the surface morphology and wear track of the coatings before and after the UNSM process using a scanning electron microscope, energy dispersive spectrometer, and three-dimensional laser scanning microscope. We observe that the wear track of the Ni-Cr coating after the UNSM process is lower than that of the as-sprayed one. Thus, we confirm that the UNSM process has a significant influence on the improvement of the tribological performance of the Ni-Cr composite coating.
THE PECULIARITY AND MANAGEMENT OF THE ENTERPRISES INNOVATION RISKS
Abdulla Umarov 한국로고스경영학회 2013 한국로고스경영학회 학술발표대회논문집 Vol.2013 No.5
The innovation risks peculiarity affecting on the enterprises production activities have been analyzed. The risks classification is provided, as well as recommendations for timely accounting of risks and management of risk situations typical for enterprises.
Amanov, A.,Umarov, R. Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.441 No.-
<P><B>Abstract</B></P> <P>In this study, a combination of local heat treatment (LHT) with (w/) and without (w/o) ultrasonic nanocrystal surface modification (UNSM) technique was applied to Inconel 690 alloy at room and high temperatures (RT and HT). The main purpose of this study is to investigate the influence of LHT w/ and w/o UNSM processing on the mechanical and fretting wear mitigation of Inconel 690 alloy. The surface roughness of the specimens was increased with increasing the LHT temperature w/ and w/o UNSM from RT to HT at 700 °C, while the surface hardness of the RT and HT at 300 °C specimens was increased and softening occurred at HT at 700 °C. The mechanical properties of the specimens were investigated using a tensile stress test. It was found that the stress-strain curve of the UNSM-treated at RT exhibited better mechanical characteristics in comparison with the as-received one. Moreover, the specimens treated at HT at 300 and 700 °C exhibited better results in terms of strain, but there was no significant difference in stress. The UNSM treated specimens at HT of 300 °C had better results in comparison with other specimens. In addition, the fretting wear resistance of those specimens was assessed using a ball-on-disk fretting wear tester at temperatures of 25 and 80 °C. The fretting wear resistance of Inconel 690 alloy was also increased by the combination of LHT + UNSM processing, which may be attributed to the increase in mechanical properties, increase in surface roughness, induced compressive residual stress and the presence of a nanostructured surface layer. Hence, Inconel 690 alloy with the increased mechanical properties and fretting wear resistance by the combination of LHT + UNSM processing could be beneficial for nuclear applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A local heat treatment along with UNSM treatment was employed to Inconel 690 alloy. </LI> <LI> The surface roughness was increased with increasing the temperature. </LI> <LI> The surface hardness was reduced at 700 °C, while it was increase at 300 °C. </LI> <LI> The fretting wear was mitigated by local heat treatment along with UNSM treatment. </LI> <LI> The role of local heat treatment and UNSM processing is significant. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
REFORMS FOR THE IMPROVEMENT OF UZBEKISTAN FOREIGN TRADE
Abror Juraev,Bekhzod Umarov 한국로고스경영학회 2006 한국로고스경영학회 학술발표대회논문집 Vol.- No.-
Some obstacles exist that prevent foreign trade of Uzbekistan from the potential it could reach. The main obstacles can be described as low competitiveness of Uzbek goods in the world markets, high rates of export-import and investment insurance services, high tariffs, relatively low technological level of enterprises, differences in technical and quality requirements and others. These problems have depressive effects on levels of Uzbek export and inflow of foreign direct investments. There are opportunities to solve the problems and improve quantitative and qualitative indicators of Uzbek foreign trade. The article is a research on possible solutions to problems and contains recommendations. It is concluded that further liberalization reforms are needed.